The Crystal Structure of Orthocetamol Solved by 3D Electron Diffraction

Area of Science:

• Crystallography
• Materials Science
• Pharmacology

Background:

• Orthocetamol is a regioisomer of paracetamol with analgesic and anti-arthritic potential.
• Its crystal structure has remained undetermined for over a century due to difficulties with single crystal growth for X-ray diffraction.

Purpose of the Study:

• To determine the crystal structure of orthocetamol.
• To establish a new method for crystal structure determination when X-ray diffraction is not feasible.

Main Methods:

• Ab-initio structure determination using 3D electron diffraction.
• Low-dose electron acquisition method.
• Utilized a dedicated single-electron detector for recording diffracted intensities.

Main Results:

• The crystal structure of orthocetamol was successfully determined.
• The structure is monoclinic with a pseudo-tetragonal cell.
• Multiple twinning was observed on a nanometer scale.

Conclusions:

• 3D electron diffraction provides a viable solution for determining the crystal structure of orthocetamol.
• This technique establishes a new standard for total structure solution when X-ray diffraction and electron microscopy fail.